From Karen Armstrong’s A History of God: The 4,000-Year Quest of Judaism, Christianity and Islam:

Denys’s God has two aspects: one is turned toward us and manifests himself in the world; the other is the far side of God as he is in himself, which remains entirely incomprehensible.  He “stays within himself” in his eternal mystery, at the same time as he is totally immersed in creation.  He is not another being, additional to the world.  Deny’s method became normative in Greek theology.  In the West, however, … some imagined that when they said ” God,” the divine reality actually coincided with the idea in their minds.  Some would attribute their own thoughts and ideas to God – saying that God wanted this, forbade that and had planned the other – in a way that was dangerously idolatrous.